Poor coonection during landline calls

[Danno]

I have been having issues with calling landlines. I can usually hear the person on the other end but they can't hear me. This issue is only a calls to landlines problem as calling mobiles is always fine. 

This was happening on my previous sim and phone and I expected an upgrade to resolve the issue with a new sim card and new number, unfortunately the problem still occurs. 

I've called Three and they're unsure of the issue. 

[KateS]

Hey Danno,

Thanks for getting back to me.

Could you turn off Wi-Fi calling and let me know if it's still the same?

Also, do you find any call you make to a landline, while out and about, is the same, no matter the location?

Could you also provide me with the make and model of your device, please.

Thanks,
Kate

[KateS]

Hey Danno,

I'm sorry to hear you're having trouble with calling landlines, this must be frustrating.

Did you try following the steps as advised by @tarantella , at all?

Could you also pop your postcode into our Network Status Checker and let me know if any issues are reported in the area, or work currently taking place, please?

Thanks,
Kate

[tarantella]

Try switching off wifi-calling and see if that helps.

If you haven't already, put your postcode into the coverage checker.

Also, check network status in your area to see if there's any ongoing work or maintenance. 

Failing all of that,  have a chat with Customer Services. 

If none of that helps,  raise a complaint.

[Danno]

I've tried turning the phone on/off, I've manually selected on the sim settings Three; and the area checker is showing as no faults in the area. 

The only thing I haven't done is turning off wifi calling, however I've called landlines when I'm not connected to WiFi anf had similar issues.